Slides in this set

Slide 1

Alcohol· The general formula for alcohol is CnH2n+1OH.· When naming an alcohol if there are more than one OH we use di- , tri-, tetra-, ect...· Alcohols can be classified as Primary (1o), Secondary (2o), or tertiary (3o).· A primary alcohol has the ­OH group at the end of a chain. (IE the main Carbon atom is attached to only one other Carbon atom).· A secondary alcohol has the ­OH group in the body of the chain. (IE The main Carbon atom is attached to two carbon atoms in the middle of the chain).· A tertiary alcohol has the ­OH group in the body of the chain and attached to a branch.· Alcohols have higher melting and boiling points because the Oxygen molecule allows hydrogen bonds to form between the molecules.· Alcohols are soluble in water because hydrogen bonds can form between the ­OH groups and water molecules.…read more

Slide 2

Alcohol· Alcohols are very useful in industry because they can be used as an intermediate.· They are easily made and easily converted into other compounds.· EG Methanol can be used as a starting material for making other organic chemicals.Ethanol· Ethanol is considered the most important alcohol.· It is used as an intermediate in the manufacture of other organic chemicals.· It is often used as a solvent in cosmetics EG After shave, perfume.· It is used in the manufacturing of drugs, detergents, inks and coatings.· It is made by reacting ethene with steam using a catalyst: Phosphoric acid.· It can also be made from sugars by fermentation (Used to make alcohol).· Beers have 5% ethanol, wines have 12%. Spirits, such as gin and whisky, contain 40% ethanol; these have been concentrated by distillation.…read more

Slide 3

Ethene is produced when crude oil fractions are cracked. Alcohol· The main sources is from ethane but some comes from the naphtha fraction.· Ethene is hydrated, which means that water is added across the double bond.· CH2=CH2 + H2O C2H5OH With a phosphoric acid catalyst· During fermentation, carbohydrates from plants are broken down into sugars, and then converted into ethanol by the action of enzymes from yeast.· The carbohydrates come from the crops such as sugar cane and sugar beet. Starting material Crude oil non- renewable Carbohydrates (sugars) renewableMethod Cracking and dehydration Fermentation and distillationRate of reaction Fast SlowType of process Continuous batchPurity Essentially pure Aqueous solution of ethanol is produced…read more

Slide 4

The key steps in the break down of sugar in a process called Alcohol anaerobic respiration: · Enzymes from yeast C6H12O6 (aq) 2C2H5OH (aq) + 2CO2 (g) · The rate of this chemical reaction is affected by temperature. It is slow at low temperatures by the enzymes are made ineffective if the temperature is too high. A compromise temperature of about 35oC. · Air is kept out of the fermentation vessels to provent oxidation of ethanol to ethanoic acid (the acid in vinegar). · Once the fermenting solution contains about 15% ethanol the enzymes are unable to function and fermentation stops. · EthanolCarbon is useful as a motor fuel when dioxide absorbed mixed Carbon dioxide with petrol. released Photo synthesis in the growing plant Fermentation 6H2O (aq) + 6CO2 (g) C6H12O6 (aq) 2C2H5OH (aq) + 2CO2 (g) Combustion C6H12O6 (aq) + 6O2 (g) 2C2H5OH (aq) + 6O2 (g) 4CO2 (g) + 6H2O (aq)6 molecules of CO2 absorbed 6 molecules of CO2 released…read more

Slide 5

Alcohol· Many conventional petrol engines will run on ethanol, or mixtures of petrol and ethanol, with little modification, and much of the petrol sold in the UK at present has 5 ­ 10% ethanol added.· Ethanol made from ethene is not renewable fuel because it comes from crude oil. However, ethanol made by fermentation is renewable because the sugars come from plants such as sugar cane and beet, which can be grown annually.· Cars release Carbon dioxide into the atmosphere which is associated with global warming and climate change.· Ethanol made from fermentation is sometimes termed as carbon- neutral fuel as it was obtained from photosynthesis.· Ethene is a vital industrial chemical; it is the starting material for poly(ethene) and many other important chemicals.· We could produce ethene by dehydrating ethanol made from sugar and this would give us renewable source of ethene.· At present ethene is made from crude oil and then converted into ethanol.· In the future it may become more economical to make ethene from ethanol made by fermentation.…read more

Slide 6

AlcoholCombustion· C2H5OH (l) + 3O2 (g) 2CO2 (g) + 3H2O (l)· Ethanol is often used as a fuel.Oxidation· Alcohols can also be oxidised gently and in stages.· Primary alcohols are oxidised to aldehydes (R2CHO).· Secondary alcohols are oxidised to Ketones (R2CO).· Tertiary alcohols are not easily oxidised.· This is because oxidation would need a C-C bond to break.· Ketones do not oxidise further for the same reason.· Many aldehydes and ketones have pleasant smells.The experimental details· A solution of potassium dichromate, acidified with dilute sulphuric acid, is often used to oxidise alcohols to aldehydes and ketones.· It is the oxidising agent.· In the reaction, the orange dichromate (VI) ions are reduced to green chromium (III) ions.…read more